JP5557106B2 - In-mold coating mold and in-mold coating method - Google Patents

Description

  In the present invention, after a resin molded product is molded in a mold, a resin molding mold, which is one of the molds, is replaced with a coating film forming mold, and a paint is formed in a gap formed between the molded product The present invention relates to a mold for in-mold coating and a method for in-mold coating, in which a surface of a molded product is coated (also referred to as a coating film or a coating film) by injecting.

  2. Description of the Related Art Conventionally, as a method for improving the decorativeness of a resin molded product, decoration by a coating method in which a paint is applied to the surface is often used. In the conventional coating method, it is common to take out a molded product that has been injection molded in a mold and then apply a paint to the surface of the molded product by spraying or dipping. The applied paint is then cured to form a strong coating film, covering the surface of the molded product, decorating and protecting the surface.

In recent years, an in-mold coating method (so-called in-mold coating) in which resin molding and coating with a paint are performed in the same mold has been proposed for the purpose of omitting the steps of the coating method.
In this method, after the resin is injection-molded in the mold, the mold is slightly opened to create a gap between the resin molded product and the mold cavity surface. Then, after injecting the paint into the gap using a paint injection machine, the mold is re-clamped to uniformly extend the surface of the molded product, and then cured to coat.

  According to the in-mold coating molding method, since the molding of the thermoplastic resin and the covering are performed in the same mold, the cost can be reduced by omitting the process. At the same time, the dust floating in the air hardly adheres to the coating film before curing and becomes defective, and a high quality product can be obtained. Therefore, the use of the in-mold coating method is being studied especially for automobile parts and the like that require high quality for appearance.

  However, in this in-mold coating method, since the formation of the gap for injecting the paint is based on the retreating operation of the movable platen, the formation of the gap requires advanced position control and the maintenance means for the gap. Moreover, many gaps are formed in front of the molded product due to the retraction of the movable mold, and the vertical side surface parallel to the moving direction of the movable mold remains in contact with the cavity surface, and the gap is not easily formed. Therefore, painting on the vertical side surface of a molded product such as a box shape has a problem that it is difficult to adjust the thickness of the coating film, and decorative molding is limited to a molded product of a limited form. .

  In order to solve this problem, Patent Document 1 discloses a coating technique developed from the in-mold coating method. In this technique, after the resin molding, the mold on the design side is changed from resin molding to coating film formation, and the mold is tightened again. The cavity surface of the coating film forming mold has a shape capable of forming a thin gap into which the paint is put between the resin mold product and the mold closed. For this reason, since the gap for putting the paint can be formed not only on the front surface of the molded product but also on the vertical side surface, three-dimensional coating can be applied to the box-shaped molded product.

  Patent Document 2 discloses a technique that enables partial coating on a design surface of a resin molded product by applying a coating method within a mold and forming a coating film only on a desired portion. Yes. In this method, by providing a plurality of grooves on the mold surface at the boundary between the part to be painted and the part not to be painted, and using the shrinkage when the resin is solidified and cooled, the side of the groove and the resin are brought into strong contact with each other. Then, the paint flow is sealed to form the boundary of the coating film, and partial coating is performed.

JP 2003-334838 A JP-A-2005-335123

However, the in-mold coating technique described in Patent Document 1 has an advantage that the decorative coating can be performed on the vertical side surface of the box-shaped molded product, but partial coating that limits the range in which the coating film is formed is possible. No technology relating to multi-color coating in which a plurality of colors of paint is applied is disclosed.
Moreover, in the partial coating described in Patent Document 2, it is necessary to provide protrusions and recesses at the boundary of the coating film, and it is difficult to provide the boundary of the coating film on the same surface without a step, which is a design problem. There was a problem that it could not be avoided.

In order to solve the above problems, in the present invention ,
With the common mold holding the resin molded product, it is closed with the coating film forming mold, and a gap for putting the paint between the resin molded product and the coating film forming mold and a resin sealing material for partitioning the gap are provided. Mold that fills the groove with a resin sealant and then fills the gap with a paint from a paint injection machine and cures it, thereby partially painting the surface of the resin molded product Use the inner coating mold. Then, molding of the resin molded product and partial or multicolor coating of the surface thereof are performed in the mold.

(1) When the surface of a plastic molded product is painted in a mold, efficient partial coating and multicolor coating are possible.
(2) The boundary line of the coating film is clear and the decoration becomes bright, and the appearance of the molded product can be improved.

It is an Example of this invention, and is a figure which shows a mold clamping apparatus and a metal mold | die. It is a figure showing the procedure of shaping | molding and in-mold coating based on a 1st Example. It is a figure showing the procedure of shaping | molding and in-mold coating based on a 2nd Example. It is a figure showing the procedure of shaping | molding and in-mold coating based on a 3rd Example. It is a figure showing the procedure of shaping | molding and in-mold coating based on a 4th Example. It is a figure which shows the external appearance of the plastic molded product partially coated by this invention. It is a figure which shows the external appearance of the two-color-painted plastic molded product by this invention.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a mold clamping device, a part of an injection device, and a mold of a resin injection molding machine that performs in-mold coating according to the present invention, and is common to each embodiment.
The lower side of the mold clamping device 10 is supported by the machine base 11. On the machine base 11, a fixed platen 12 is fixedly placed via a key 13, and a resin molding die 40 is attached. In addition, four tie bars 16 that receive a clamping force penetrate through the four corners of the fixed platen 12 and are fixed by fixing nuts 17.

  On the left side of the fixed platen 12, an intermediate platen 20 to which a common mold A44 and a common mold B45 are attached is slidably mounted. A rotary table 21 is fixed below the intermediate platen 20, and the lower side is connected to a slide table 24 via a rotary bearing 23. A rotation drive device (not shown) is installed between the slide table 24 and the turntable 21 so that the intermediate platen 20 and the common mold can be rotated 180 °. Further, since the slide table 24 is connected to the machine base 11 via the slide rail 26 and the slide block 27, the slide table 24 can be opened and closed with extremely low sliding resistance. A mold opening / closing operation driving device (not shown) is incorporated between the machine base 11 and the slide table 24, and the intermediate platen 20 and the common mold can be opened and closed. Since the extrusion mechanism is incorporated in the intermediate platen 20, it is possible to remove the molded product attached to the common mold.

On the left side of the intermediate platen 20, a movable platen 14 holding a coating film forming mold 42 is slidably mounted on the machine base 11 by a slide base 15 fixed to the lower side. The left side of the movable platen 14 is connected to a toggle mechanism or a mold clamping cylinder (not shown) so that a mold opening / closing operation and a mold clamping force can be applied.
By rotating the intermediate platen 20 by 180 °, the common mold A44 and the common mold B45 can be closed together with either the resin molding mold 40 or the coating film forming mold 42. The common mold A44 and the common mold B45 are the same.
Then, by interlocking the intermediate platen 20 and the movable platen 14, the resin molding die 40, the common die A44, the coating film forming die 42, and the common die B45 can be opened and closed, At the same time, a mold clamping force can be applied.

The fixed platen 12 that holds the resin molding die 40 has a hole for inserting the main injection device 30 at the center, and the main injection nozzle 31 mounted at the tip of the main injection device 30 is inserted into the resin molding die. The entrance of the main resin flow path 41 of the mold 40 can be touched. Thereby, it has a structure in which molten resin can be injected and filled into a cavity formed between the resin molding die 40 and the common die A44.
In addition, the coating film forming mold 42 is a paint that can inject liquid paint into the coating cavity formed between the resin molded product attached to the common mold B45 through the paint injection hole 49. An injector 47 is attached.

  Here, an example of the structure of the paint injector 47 will be briefly described. The coating material injection machine 47 (also referred to as an injector) in the present embodiment is attached to the coating film forming mold 42 and is cavityd through the coating material injection hole 49 provided in the coating film forming mold 42. It is comprised so that a coating material can be inject | poured into an internal clearance gap. The coating material injector 47 is driven by a driving device (not shown), and can accurately inject the coating material supplied therein by a desired amount with an appropriate pressure.

  Further, as in Examples 3 and 4 to be described later, when the resin seal groove formed between the resin molded product of the common mold B45 and the coating film forming mold 42 is filled with resin, the sub resin flow A passage 48 is provided, and the molten resin is filled from the sub injection device 32. In FIG. 1, the sub-injection device is shown to touch the coating film forming mold 42 from below, but it is of course possible to make a configuration in which the sub-injection device is touched from the side.

The first embodiment will be described with reference to FIG. Figures (a) to (g) show the steps from resin molding to in-mold coating and removal. The first embodiment of the present invention is described as a reference for understanding the present invention.
First, as shown in (a), the molten resin is injected from the main injection device 30 in a state in which the mold for resin molding 140 and the common mold 144 are closed and a clamping force is applied. The molten resin is filled into the cavity through the main resin flow channel 141. The molten resin in the cavity is cooled with time to become a solid resin molded product 150. Thereafter, the mold is opened. As shown in (b), the resin molded product 150 has a mold shape that is attached to the common mold 144 side. Next, the intermediate platen is rotated 180 ° so that the common mold 144 and the resin molded product 150 are opposed to the coating film forming mold 142 provided with the paint injection machine 147 as shown in FIG.

When the molds are closed from this state, a paint cavity gap 152 is formed between the resin molded product 150 and the coating film forming mold 142 as shown in FIG. The cavity surface of the coating film forming mold 142 is processed so that the paint cavity gap 152 is formed only on the surface of the resin molded product 150 that needs to be partially coated. Therefore, a seal surface 153 is formed in a portion that does not need to be painted, and is in direct contact with the resin molded product so that the paint does not flow in.
The paint cavity gap 152 communicates with the paint injector 147 through the paint injection hole 149. Then, as shown in (e), the paint injection machine is operated to inject the paint, thereby forming the in-cavity paint 155. If the injection takes time, the thermosetting of the paint proceeds in the paint cavity gap 152 until the completion of the injection, causing a short shot of the paint and a decrease in surface properties. Therefore, it is preferable to complete the injection as soon as possible.
When time elapses and the paint is cured to become a coating film 156, the mold is opened as shown in (f). Then, the extrusion mechanism is operated and removed from the common mold 144 as shown in (g) to obtain a partially coated resin molded product. The resin molded product is partially coated as shown in FIG.

By processing the cavity surface of the coating film forming mold 142 so that the paint cavity gap 152 is formed not only on the front surface of the resin molded product 150 but also on the vertical side surface, It can be formed uniformly and can be painted three-dimensionally.
The molded resin material is preferably one that is easy to mold and has good adhesion to the thermosetting paint. Also, paints with excellent curability, adhesion, appearance, and weather resistance are suitable.

  In the figure, the coating film is drawn thick so that the molding process and the painting process can be easily understood. However, actually, the thickness of the resin molded product is about 2 to 3 mm, the thickness of the coating film is about 0.05 to 0.2 mm, and the coating film is sufficiently thinner than the resin molded product.

  If a mold clamping apparatus as shown in FIG. 1 is used, resin molding by a resin mold and a common mold, and in-mold coating by a coating film forming mold and a common mold can be performed simultaneously during the mold clamping operation. . Therefore, one coated resin molded product can be obtained by one mold opening / closing operation and common mold rotating operation, and it becomes possible to carry out highly productive resin molded product in-mold coating.

  Also, as a mold clamping device with another structure, it is possible to install a common mold on the movable platen side and slide the resin molding mold and coating film forming mold on the fixed platen side so that they can be exchanged. It is. In this case, one painted resin molded product is obtained by two mold opening / closing operations and a mold slide exchanging operation.

Next, a second embodiment will be described with reference to FIG. Since the second embodiment has many steps in common with the first embodiment, different steps will be described with reference to FIGS. The second embodiment of the present invention is also described as a reference for understanding the present invention.
After molding, the resin molded product 250 is opposed to the coating film forming mold. The coating film forming mold is provided with two paint injection machines 247 as shown in (c), and a seal projection 254 is formed on the cavity surface. When the molds are closed, the resin molded product 250 and the seal projection 254 come into contact with each other as shown in FIG. Each paint cavity gap (252a, 252b) communicates with another paint injector (247a, 247b). The paint is injected from each of the injectors, and the cavity for paint is filled with the paint in the cavity (255a, 255b) as shown in (e). When the paint is cured to form a coating film, the mold is opened as shown in (f). Two types of coating films (256a, 256b) are formed on the surface of the resin molded product 250. Therefore, if different color paints are put in the paint injection machine, the resin molded product 250 becomes a molded product decorated with two colors (multicolor).

  As shown in FIG. 7, the molded product is decorated with two-color coating films (56a, 56b). Furthermore, when the seal projections are appropriately arranged and the paint cavity gap is divided into three places, it is possible to paint in three colors by communicating each with a paint injector.

A third embodiment will be described with reference to FIG. In the third embodiment, the partition of the coating cavity gap for partial coating is formed by filling the resin seal groove with molten resin.
As in the first embodiment, as shown in (a), the molten resin is injected from the main injection device 30 in a state where the resin molding die 340 and the common die 344 are closed and a clamping force is applied. The molten resin passes through the main resin flow path 341 and is filled into the mold cavity, and is then cooled and solidified to form a resin molded product 350. Next, the mold is opened. As shown in (b), the resin molded product has a mold shape that is attached to the common mold 344 side. Thereafter, the intermediate platen is rotated 180 °, and the resin molded product 350 is opposed to the coating film forming die 342 as shown in FIG. The coating film forming mold 342 is provided with a paint injector 347 and a sub resin flow path 348 communicating with the cavity surface. When the mold is closed, a paint cavity gap 352 and a resin seal groove 360 are formed in the cavity as shown in FIG. Thereafter, the nozzle tip of the sub injection device 32 is touched at the entrance of the sub resin flow path 348.

From this state, first, as shown in (e), the resin injection groove 32 is filled with the molten resin from the sub-injection device 32, and is cooled and solidified to form the resin sealing material 361. In the figure, the paint cavity gap 352 is shown thick for easy understanding. However, since it is actually as thin as 0.05 to 0.2 mm, the molten resin does not enter the paint cavity gap 352. Absent. Subsequently, as shown in (f), the paint is injected from the paint injector 347 to form the in-cavity paint 355. When the mold is opened after the paint is cured, the coating film 356 and the resin sealing material 361 are adhered to the surface of the resin molded product 350 as shown in (g). Then, as shown in (h), the extrusion device is driven to remove the resin molded product 350 from the common mold.
Thereafter, when only the resin sealing material 361 is removed, a partially coated resin molded product as shown in FIG. 6 can be obtained.

In this embodiment, since the boundary portion of the partially coated coating film is partitioned by the resin sealing material 361 that is in close contact with the resin molded product 350, the boundary line becomes clearer and the appearance of the resin molded product can be made more beautiful.
The resin material of the resin molded product 350 and the resin sealing material 361 is preferably in a relationship that does not completely adhere. For example, if the resin material of the resin molded product 350 is ABS or polycarbonate and the resin material of the resin seal material 361 is polyethylene or polypropylene, the resin molded product 350 and the resin seal material 36 are not strongly adhered, and the resin seal material 361 Can be easily removed. The same applies when the resin molded product 350 is made of polypropylene and the resin sealing material 361 is made of polyethylene.

  A fourth embodiment will be described with reference to FIG. Since the fourth embodiment has many steps in common with the third embodiment, only different steps will be described with reference to (c) to (g). As shown in (c), the coating film forming mold 444 is provided with two paint injection machines (447a, 447b) and a sub resin flow path 448. When the common mold holding the resin molded product and the coating film forming mold 434 are closed as shown in FIG. (452a, 452b) and a resin seal groove 460 are formed. Then, the sub injection device 32 is touched. Thereafter, as shown in (e), first, molten resin is injected and filled into the seal groove portion 460 from the sub injection device 32, and then cooled and solidified to form a resin seal material 461. Subsequently, as shown in (f), paint is injected from each paint injection machine to form in-cavity paints (455a, 455b). When the mold is opened as shown in (g) after the coating is cured, two types of coating films (456a and 46b) are formed on the resin molded product, and both the resin sealing material and 461 are attached. If the resin sealing material 461 is peeled off after being removed from the mold, a plastic molded product painted in two colors (multicolor) as shown in FIG. 7 can be obtained. The boundary line of the coating film of this molded product is clear, and it is a more beautiful painted product.

  The above-described embodiment is an example of the present invention, and the present invention is not limited by the embodiment, and is defined only by matters described in the claims, and other embodiments are also possible. It can be implemented.

  It becomes possible to easily and efficiently produce partially painted resin molded products and multicolor coated resin molded products used as automobile parts and the like in a molding factory.

DESCRIPTION OF SYMBOLS 10 Clamping machine 11 Machine base 12 Fixed platen 13 Key 14 Movable platen 15 Sliding table 16 Tie bar 17 Fixed nut 20 Intermediate platen 21 Rotating table 23 Rotating bearing 24 Slide table 26 Slide rail 27 Slide block 30 Main injection device 31 Main injection nozzle 32 Sub-injection device 40 Mold for resin molding 41 Main resin flow path 42 Mold for coating film formation 44 Common mold A
45 Common mold B
47 Paint Injection Machine 48 Sub-Resin Flow Channel 49 Paint Injection Hole 50 Resin Molded Product 52 Cavity Gap for Paint 53 Seal Surface 54 Seal Protrusion 55 Paint in Cavity 56 Paint Film 60 Seal Groove 61 Resin Seal Material

Claims (5)

An in-mold coating mold comprising a resin molding mold, a common mold, a coating film forming mold having a coating material injection machine and a resin flow path,
A resin molded product can be formed by injecting and filling a molten resin into a cavity formed between the resin molding die and the common die, and then cooling and solidifying the resin. Is possible,
To close the gap between the resin molded product and the coating film forming mold and the gap between the resin molded product and the coating film forming mold when the common mold holds the resin molded product. A groove portion for filling the resin seal material is formed, and after filling the groove portion with a resin seal material, the surface of the resin molded product is partially painted by filling the gap with a paint from a paint injection machine and curing it. Is possible,
A mold for partial painting inside a mold. A mold for in-mold painting according to claim 1 ,
The coating film forming mold includes a plurality of paint injection machines,
The common mold is closed with the coating film forming mold while holding the resin molded product, and a plurality of gaps are provided between the resin molded product and the coating film forming mold. A groove portion for filling a resin seal material for partitioning is formed, and after filling the groove portion with a resin seal material, the plurality of gaps are filled with a paint from each paint injection machine and cured, whereby the resin molded product It is possible to paint the surface in multiple colors,
Multi-color painting mold in the mold characterized by that. An in-mold coating method using the mold according to claim 1 ,
A step of closing the resin mold and the common mold, injecting and filling molten resin into a cavity formed therebetween, and then cooling and solidifying to mold a resin molded product;
Opening the resin mold and the common mold, and closing the common mold and the coating film forming mold in a state where the common mold holds the resin molded product;
Filling a molten resin into a groove portion into which the resin sealing material formed between the resin molded product and the coating film forming mold is placed;
Filling and curing a paint from a paint injecting machine into a gap partially formed between the resin molded product and the coating film forming mold; and
Mold part coating method characterized by comprising the. An in-mold coating method using the mold according to claim 2 ,
A step of closing the resin mold and the common mold, injecting and filling molten resin into a cavity formed therebetween, and then cooling and solidifying to mold a resin molded product;
Opening the resin mold and the common mold, and closing the common mold and the coating film forming mold in a state where the common mold holds the resin molded product;
Filling a molten resin into a groove portion into which the resin sealing material formed between the resin molded product and the coating film forming mold is placed;
Filling a plurality of gaps formed between the resin molded product and the coating film forming mold from each paint injection machine and curing the paint,
Mold multicolor coating method characterized by comprising the. The in-mold coating method according to any one of claims 3 and 4 ,
A resin in which the material of the resin molded product and the resin sealing material does not completely adhere to each other, and includes a step of removing the resin sealing material after removing the coated resin molded product from the mold. In-mold painting method.

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